Optical element and reflection-type liquid crystal display system using the same

ABSTRACT

The present disclosure provides an optical element used in a reflection-type liquid crystal display system. The optical element includes a substrate, and a plurality of prisms formed on a surface of the substrate and sequentially arranged along a first direction. Each of the plurality of prisms includes a plurality of sub-prisms sequentially arranged along the first direction with refractive indexes sequentially decreased.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based upon International Application No.PCT/CN2018/088434, filed on May 25, 2018, which claims priority toChinese Patent Application No. 201710776139.9, filed on Aug. 31, 2017,the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to the field of display, andmore particularly, to an optical element and a reflection-type liquidcrystal display system using the optical element.

BACKGROUND

In conventional reflective liquid crystal display systems, an edge-litlight guide plate is used as a front light source system, most ofemergent light is in a large angle direction, such that incident lightentering liquid crystal glass is also in a large angle direction. Aftercolor separation through color film, three-color light reflected backmay be unable to enter the color film of corresponding color because thereflection angle is larger, and thus a lot of light energy may be lost.

The above-mentioned information disclosed in this Background section isonly for the purpose of enhancing the understanding of background of thepresent disclosure and may therefore include information that does notconstitute a prior art that is known to those of ordinary skill in theart.

SUMMARY

The present disclosure is to provide an optical element and areflection-type liquid crystal display system using the optical element.

Other features and improvements of the present disclosure will becomeapparent from the following detailed description, or in part, beacquired by practice of the present disclosure.

According to a first aspect of the present disclosure, there isdisclosed an optical element used in a reflection-type liquid crystaldisplay system. The optical element includes a substrate, and aplurality of prisms formed on a surface of the substrate. Each of theplurality of prisms comprises a plurality of sub-prisms arranged side byside along a first direction with refractive indexes sequentiallydecreased.

In an exemplary arrangement of the present disclosure, the plurality ofprisms are separated from one another with a separation distance whichis at least maintained so that a light propagation path corresponding toone of the plurality of prisms has no effect on respective lightpropagation paths corresponding to other prisms of the plurality ofprisms.

In an exemplary arrangement of the present disclosure, the sub-prismhaving a maximum refractive index among the plurality of sub-prisms islarger than other sub-prisms in thickness.

In an exemplary arrangement of the present disclosure, a thickness ofthe sub-prism having the maximum refractive index among the plurality ofsub-prisms is not less than a sum of respective thicknesses of the othersub-prisms.

In an exemplary arrangement of the present disclosure, the number of theplurality of sub-prisms is six.

In an exemplary arrangement of the present disclosure, a differencebetween the refractive indexes of any two adjacent sub-prisms among theplurality of sub-prisms is smaller than 0.05.

In an exemplary arrangement of the present disclosure, the plurality ofprisms extend, on the surface of the substrate, along a second directionperpendicular to the first direction, and a length of the prism in thesecond direction is equal to that of the substrate in the seconddirection.

In an exemplary arrangement of the present disclosure, a cross sectionof each of the prisms taken by a plane extending along the firstdirection and perpendicular to the surface of the substrate is arectangle.

In an exemplary arrangement of the present disclosure, a long side ofthe rectangle is perpendicular to the surface of the substrate.

In an exemplary arrangement of the present disclosure, a cross sectionof each of the prisms taken by a plane extending along the firstdirection and perpendicular to the surface of the substrate is an arc,and a convex surface of each of the prisms faces toward the firstdirection.

According to a second aspect of the present disclosure, there isprovided a reflection-type liquid crystal display system. Thereflection-type liquid crystal display system including areflection-type liquid crystal panel, an optical element according toany one of the above arrangements arranged on a light exiting side ofthe reflection-type liquid crystal panel, and a light source and anedge-lit light guide plate arranged on a light exiting side of theoptical element.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the present disclosure.

This section provides a general summary of various implementations orexamples of the technology described in the present disclosure, and isnot a comprehensive disclosure of its full scope or all of its features.

BRIEF DESCRIPTION OF THE DRAWINGS

The above features and improvements of the present disclosure willbecome more apparent by describing in detail the exemplary arrangementsthereof with reference to the accompanying drawings.

The accompanying drawings herein are incorporated in and constitute apart of this specification, illustrate arrangements conforming to thepresent disclosure and together with the description serve to explainthe principles of the present disclosure. Apparently, the accompanyingdrawings in the following description show merely some arrangements ofthe present disclosure, and persons of ordinary skill in the art maystill derive other drawings from these accompanying drawings withoutcreative efforts.

FIG. 1 illustrates an overall schematic structural side view of anoptical element according to an exemplary arrangement of the presentdisclosure;

FIG. 2 illustrates an overall schematic structural top view of anoptical element according to an exemplary arrangement of the presentdisclosure;

FIG. 3 illustrates a schematic side view of an optical path simulationof an optical element according to an exemplary arrangement of thepresent disclosure;

FIG. 4 illustrates a schematic side view of a prism in an opticalelement according to another exemplary arrangement of the presentdisclosure;

FIG. 5 illustrates a schematic side view of a prism in an opticalelement according to still another exemplary arrangement of the presentdisclosure;

FIG. 6 illustrates a schematic diagram of a reflection-type liquidcrystal display system according to an exemplary arrangement of thepresent disclosure;

FIG. 7 illustrates a schematic diagram of a reflection-type liquidcrystal display system according to another exemplary arrangement of thepresent disclosure; and

FIG. 8 illustrates a schematic diagram of a reflection-type liquidcrystal display system according to still another exemplary arrangementof the present disclosure.

DETAILED DESCRIPTION

Exemplary arrangements will be described more comprehensively byreferring to accompanying drawings now. However, the exemplaryarrangements may be carried out in various manners, and shall not beinterpreted as being limited to the arrangements set forth herein.Furthermore, the described features, structures, or characteristics maybe combined in any suitable manner in one or more arrangements. In thefollowing description, numerous specific details are provided to providea thorough understanding of the arrangements of the present disclosure.Those skilled in the art will recognize, however, that the technicalsolution of the present disclosure may be practiced without one or moreof the specific details described, or that other methods, components,materials, etc. may be employed.

It is to be pointed out that in the accompanying drawings, sizes oflayers and regions may likely be exaggerated for clarity ofillustration. In addition, it may be understood that when an element orlayer is referred to as being “on” another element or layer, it may bedirectly on the other element, or intervening layers may be present.Furthermore, it may be understood that when an element or layer isreferred to as being “beneath” another element or layer, it may bedirectly beneath the other element, or at least one intervening layer orelement may be present. Moreover, it also may be understood that when alayer or element is referred to as being “between” two layers or twoelements, it may be unique layer between the two layers or two elements,or at least one intervening layer or element may be present. Throughoutthe specification, similar reference numerals indicate similar elements.

At present, in a part of the reflective liquid crystal display systems,multilayer scattering films specially designed may be additionallyarranged to reduce the direction of large-angle emergent light from theedge-lit light guide plate. However, the use of the multilayer filmmaterials makes the overall reflection-type liquid crystal displaystructure become complicated. Furthermore, the controllable light islimited in direction, and the angle can not be changed ideally.

Therefore, how to increase a light utilization efficiency of a frontlight source system used in the reflection-type liquid crystal displaysystem is a technical problem to be solved urgently at present.

The present disclosure provides an optical element and a reflection-typeliquid crystal display system in which the optical element is used. Theoptical element includes: a substrate; and a plurality of prisms formedon a surface of the substrate and sequentially arranged along a firstdirection. Any one of the plurality of prisms includes a plurality ofsub-prisms sequentially arranged along the first direction withrefractive indexes sequentially decreased. A prism array system composedof a plurality of prisms is additionally arranged between a light sourceand a reflection-type liquid crystal panel, each prism is composed of aplurality of sub-prisms, and refractive indexes of the plurality ofsub-prisms gradually decrease from a near end to light source to a farend from light source. In this way, the deflection of an angle ofemergent light from the light source may be effectively realized, theangle of the emergent light may be reduced, such that light enteringliquid crystal glass is close to a vertical direction, the energy ofexploitable light entering the reflection-type liquid crystal displaysystem is enhanced, and the light utilization efficiency and the screenbrightness of the reflection-type liquid crystal panel are increased.

The optical element and the reflection-type liquid crystal displaysystem in which the optical element is used provided by the presentdisclosure are described in detail with reference to the accompanyingdrawings, in which FIG. 1 illustrates an overall schematic structuralside view of an optical element according to an exemplary arrangement ofthe present disclosure; FIG. 2 illustrates an overall schematicstructural top view of an optical element according to an exemplaryarrangement of the present disclosure; FIG. 3 illustrates a schematicside view of an optical path simulation of an optical element accordingto an exemplary arrangement of the present disclosure; FIG. 4illustrates a schematic side view of a prism in an optical elementaccording to another exemplary arrangement of the present disclosure;FIG. 5 illustrates a schematic side view of a prism in an opticalelement according to still another exemplary arrangement of the presentdisclosure; FIG. 6 illustrates a schematic diagram of a reflection-typeliquid crystal display system according to an exemplary arrangement ofthe present disclosure; FIG. 7 illustrates a schematic diagram of areflection-type liquid crystal display system according to anotherexemplary arrangement of the present disclosure; and FIG. 8 illustratesa schematic diagram of a reflection-type liquid crystal display systemaccording to still another exemplary arrangement of the presentdisclosure.

FIG. 1 illustrates an overall schematic structural side view of anoptical element according to an exemplary arrangement of the presentdisclosure. As shown in FIG. 1, the optical element arranged withrespect to an edge-lit light guide plate 1 (however, the presentdisclosure is not limited thereto, which may be not the edge-lit lightguide plate 1 but a direct light source emitting light at a certainangle) includes: a substrate 2, and a plurality of prisms 3 sequentiallyarranged along a first direction (no matter the edge-lit light guideplate or the direct light source emitting light at a certain angle isused, the first direction is a direction from a near end to light source(not shown in FIG. 1) to a far end from the light source). The prisms 3includes a plurality of sub-prisms such as a sub-prism 31, a sub-prism32, a sub-prism 33, a sub-prism 34, a sub-prism 35 and a sub-prism 36sequentially arranged starting from a location closest to the near endto the light source. The refractive index of the sub-prism 31 is n, therefractive index of the sub-prism 32 is n1, the refractive index of thesub-prism 33 is n2, the refractive index of the sub-prism 34 is n3, therefractive index of the sub-prism 35 is n4, the refractive index of thesub-prism 36 is n5, and n>n1>n2>n3>n4>n5. The sub-prism 31, thesub-prism 32, the sub-prism 33, the sub-prism 34, the sub-prism 35 andthe sub-prism 36 are sequentially arranged to form a complete prism 3. Aplurality of prisms 3 form an array arranged on the surface of thesubstrate 2, and an air interface is provided between the prisms 3. Inthe prism according to the present disclosure, a plurality of sub-prismswith varied refractive indexes (for example, n, n1, n2, n3, . . . ) maybe arranged, generally n>n1>n2>n3> . . . , and the refractive indexesthereof gradually decrease from the near end to the light source to thefar end from the light source. Six sub-prisms are taken as an example inthe following example.

FIG. 2 illustrates an overall schematic structural top view of anoptical element according to the present disclosure. The optical elementincludes a substrate 2 and a prism 3. The prism 3 includes a sub-prism31, a sub-prism 32, a sub-prism 33, a sub-prism 34, a sub-prism 35 and asub-prism 36 sequentially arranged starting from a location closest tothe near end to the light source. The sub-prism 31, the sub-prism 32,the sub-prism 33, the sub-prism 34, the sub-prism 35 and the sub-prism36 are rectangular solids (a cross section of each prism taken by aplane extending along the first direction and perpendicular to thesurface of the substrate is a rectangle, and a long side of therectangle is perpendicular to the surface of the substrate), and extend,on the surface of the substrate, along a second direction perpendicularto the first direction, and a length of each of the sub-prisms 31, 32,33, 34, 35 and 36 in the second direction is equal to that of thesubstrate in the second direction. The sub-prism 31, the sub-prism 32,the sub-prism 33, the sub-prism 34, the sub-prism 35 and the sub-prism36 are sequentially arranged to form a complete prism 3 (the prism 3 isa rectangular solid or a cube, and the length of the prism 3 in thesecond direction is equal to that of the substrate 2 in the seconddirection). A plurality of complete prisms 3 form an array arranged onthe surface of the substrate 2, and an air interface is provided betweenthe prisms 3.

FIG. 3 illustrates a schematic side view of an optical path simulationof an optical element according to the present disclosure. The opticalelement includes a reflective substrate 4 and a prism 3. The prism 3includes a sub-prism 31, a sub-prism 32, a sub-prism 33, a sub-prism 34,a sub-prism 35 and a sub-prism 36 sequentially arranged starting from alocation closest to the near end to the light source. As a primary prismof the prism 3, the sub-prism 31 has a thickness T much larger thanthicknesses of the other sub-prisms of the prism 3. The thicknesses ofthe other sub-prisms may be either equal or different, which is notspecially limited as long as the thicknesses of the other sub-prisms aremuch smaller than the thickness of the sub-prism 31. The separationdistance between two prisms 3 should be maintained so that lightpropagation path of one prism has no effect on light propagation path ofanother prism. That is, light refracted by a certain prism is notincident into other prisms adjacent to this prism. As can be seen from asimulated example, when an angle of incident light α=80°, an angle ofemergent light β=30°, the light angle is greatly reduced, wherein n=1.3,n1=1.25, n2=1.2, n3=1.15, n4=1.1, n5=1.05, and an aspect ratio of therectangular cross section of the sub-prism 31 is 0.4.

The refractive index n of the sub-prism 31 according to the presentdisclosure decides a light deflection angle, but a total reflection isnot allowed to directly occur such that light deflects past a normaldirection and is directed to another side. By calculation, it may beobtained n<1.414, the angle of emergent light is β=cos⁻¹√{square rootover (n²−1)}, and the aspect ratio is

${\tan\left( {\sin^{- 1}\left( \frac{\sin\;\beta}{n} \right)} \right)}.$Furthermore, occurrence of unnecessary total reflection is avoided, anddifference between refractive indexes at each layer should be smallerthan 0.05.

In an exemplary arrangement of the present disclosure, the thickness ofthe sub-prism having the maximum refractive index among the plurality ofsub-prisms of any prism is not less than sum of the thicknesses of theother sub-prisms.

FIG. 4 illustrates a schematic side view of a prism in an opticalelement according to another exemplary arrangement of the presentdisclosure. A cross section of each of the plurality of prisms 3 and ofeach of the plurality of sub-prisms (the sub-prism 31, the sub-prism 32,the sub-prism 33, the sub-prism 34, the sub-prism 35 and the sub-prism36) taken by a plane extending along the first direction (i.e., theaforementioned direction from a near end to light source to a far end tolight source) and perpendicular to the surface of the substrate is anarc. Convex surfaces of the plurality of prisms and of the plurality ofsub-prism face toward the first direction, the refractive indexes aregradually decreased from a center of chord of the arc to outside of thearc, with a rule the same as that of the aforementioned cuboid opticalprism. The refractive index of the sub-prism 31 is n, the refractiveindex of the sub-prism 32 is n1, the refractive index of the sub-prism33 is n2, the refractive index of the sub-prism 34 is n3, the refractiveindex of the sub-prism 35 is n4, and the refractive index of thesub-prism 36 is n5, wherein n>n1>n2>n3>n4>n5.

In an exemplary arrangement of the present disclosure, a particularangle is formed between the prism as shown in FIG. 4 and the surface ofthe substrate to ensure that incident light is not incident from theconvex surfaces of the sub-prisms.

FIG. 5 illustrates a schematic side view of a prism in an opticalelement according to still another exemplary arrangement of the presentdisclosure. As shown in FIG. 5, on the basis of the prism as shown inFIG. 4, two top ends of the prism are removed such that the sub-prismshave equal heights. However, the present disclosure is not limitedthereto, the sub-prisms may have different heights.

The reflection-type liquid crystal display system of the presentdisclosure is described in detail with reference to FIG. 6.

FIG. 6 illustrates a schematic diagram of a reflection-type liquidcrystal display system according to an exemplary arrangement of thepresent disclosure; As shown in FIG. 6, the reflection-type liquidcrystal display system includes: a reflection-type liquid crystal panel61; the optical element 62 according to any one of the foregoingarrangements arranged on the reflection-type liquid crystal panel; and afront light source 63 arranged on the optical element, wherein the frontlight source 63 includes an edge-lit light guide plate 631 and a lightsource 632. The light source is positioned on a light incident side ofthe edge-lit light guide plate or at the near end to the light source ofthe edge-lit light guide plate.

FIG. 7 illustrates a schematic diagram of a reflection-type liquidcrystal display system according to another exemplary arrangement of thepresent disclosure. As shown in FIG. 7, a surface of a light-exitingside of the edge-lit light guide plate 631 has a plurality of ink dots633. Light emitted from the light source 632 entering the edge-lit lightguide plate 631 is scattered out by the ink dots 633. Incident light isincident from a side direction of the edge-lit light guide plate 631 ata larger angle, and thus the angle of emergent light is larger, suchthat after light enters the optical element 62, the angle of light maybe narrowed. In this way, the light utilization efficiency is increased.

FIG. 8 illustrates a schematic diagram of a reflection-type liquidcrystal display system according to still another exemplary arrangementof the present disclosure. An emergent light grating 634 is arrangedbetween the edge-lit light guide plate 631 and the optical element 62.An orthographic projection of the emergent light grating 634 on thesubstrate 2 is positioned within an orthographic projection, on thesubstrate 2, of the sub-prism 31 having a maximum refractive index inthe optical element 62. In this way, the emergent light from the lightguide plate 631 is directional. Specifically, light is emitted from aprism (such as the sub-prism 31) having a higher refractive index to aprism (such as the sub-prism 32 or the sub-prism 33) having a lowerrefractive index. When a plurality of optical elements 62 are arranged,correspondingly a plurality of light gratings 634 may be arranged,wherein each optical element 62 corresponds to one emergent lightgrating 634.

In the reflection-type liquid crystal display system according to anexemplary arrangement of the present disclosure, an optical elementincluding a plurality of prisms with varied refractive indexes isadditionally arranged between the edge-lit light guide plate and thereflection-type liquid crystal panel, and the refractive indexesgradually decrease from the near end to light source to the far end fromthe light source. In this way, the angle of emergent light from theedge-lit light guide plate may be reduced, the energy of exploitablelight entering the reflection-type liquid crystal display system isenhanced, and the light utilization efficiency and the screen brightnessof the reflection-type liquid crystal panel are increased.

Through the above detailed description, those skilled in the art readilyunderstand that the optical element and the reflection-type liquidcrystal display system in which the optical element is used according tothe arrangements of the present disclosure have one or more of thefollowing improvements.

According to some arrangements of the present disclosure, a prism arraysystem composed of a plurality of prisms is additionally arrangedbetween a light source and a reflection-type liquid crystal panel, eachprism is composed of a plurality of sub-prisms, and refractive indexesof the plurality of sub-prisms gradually decrease from a near end tolight source to a far end from light source. In this way, the deflectionof an angle of emergent light from the light source may be effectivelyrealized, the angle of the emergent light may be reduced, such thatlight entering liquid crystal glass is close to a vertical direction,the energy of exploitable light entering the reflection-type liquidcrystal display system is enhanced, and the light utilization efficiencyand the screen brightness of the reflection-type liquid crystal panelare enhanced.

According to some arrangements of the present disclosure, the more thesub-prisms with varied refractive indexes are, i.e., the smaller theinterface refractive index difference at each layer is, the better thedeflection effect is because unnecessary totally reflected light may bereduced.

Other arrangements of the present disclosure will be apparent to thoseskilled in the art from consideration of the specification and practiceof the disclosure disclosed here. This application is intended to coverany variations, uses, or adaptations of the present disclosure followingthe general principles thereof and including such departures from thepresent disclosure as come within known or customary practice in theart. It is intended that the specification and arrangements beconsidered as exemplary only, with a true scope and spirit of thepresent disclosure being indicated by the following claims.

It will be appreciated that the present disclosure is not limited to theexact construction that has been described above and illustrated in theaccompanying drawings, and that various modifications and changes can bemade without departing from the scope thereof. It is intended that thescope of the present disclosure only be limited by the appended claims.

What is claimed is:
 1. An optical element used in a reflection-typeliquid crystal display system, comprising: a substrate; and a pluralityof prisms formed on a surface of the substrate, wherein each prism ofthe plurality of prisms comprises a plurality of sub-prisms arrangedside by side along a first direction with respective refractive indexessequentially decreased along the first direction.
 2. The optical elementaccording to claim 1, wherein the plurality of prisms are separated fromone another with a respective separation distance which is at leastmaintained so that a light propagation path corresponding to one prismof the plurality of prisms has no effect on light propagation pathscorresponding to other prisms of the plurality of prisms.
 3. The opticalelement according to claim 1, wherein a sub-prism of the plurality ofsub-prisms of each prism having a maximum refractive index among theplurality of sub-prisms is larger than other sub-prisms of the pluralityof sub-prisms in thickness.
 4. The optical element according to claim 3,wherein a thickness of the sub-prism having the maximum refractive indexamong the plurality of sub-prisms is not less than a sum of respectivethicknesses of the other sub-prisms.
 5. The optical element according toclaim 3, wherein a number of the plurality of sub-prisms is six.
 6. Theoptical element according to claim 1, wherein a difference between therefractive indexes of two adjacent ones of the plurality of sub-prismsof each prism is smaller than 0.05.
 7. The optical element according toclaim 1, wherein the plurality of prisms extend, on the surface of thesubstrate, along a second direction perpendicular to the firstdirection, and a length of each of the plurality of prisms in the seconddirection is equal to a length of the substrate in the second direction.8. The optical element according to claim 1, wherein a cross section ofeach of the plurality of prisms taken by a plane that extends along thefirst direction and is perpendicular to the surface of the substrate isa rectangle.
 9. The optical element according to claim 8, wherein a longside of the rectangle is perpendicular to the surface of the substrate.10. The optical element according to claim 1, wherein a cross section ofeach of the plurality of prisms taken by a plane that extends along thefirst direction and is perpendicular to the surface of the substrate isan arc, and a respective convex surface of each of the plurality ofprisms faces toward the first direction.
 11. A reflection-type liquidcrystal display system, comprising: a reflection-type liquid crystalpanel; an optical element arranged on a light exiting side of thereflection-type liquid crystal panel; and a light source and an edge-litlight guide plate arranged on a light exiting side of the opticalelement, wherein the optical element comprises a substrate; and aplurality of prisms formed on a surface of the substrate, and whereinany one of the plurality of prisms comprises a plurality of sub-prismsarranged side by side along a first direction with refractive indexessequentially decreased along the first direction.
 12. Thereflection-type liquid crystal display system according to claim 11,wherein a light exiting surface of the edge-lit light guide plate has aplurality of ink dots.
 13. The reflection-type liquid crystal displaysystem according to claim 11, wherein an emergent light grating isarranged between the edge-lit light guide plate and the optical element.14. The reflection-type liquid crystal display system according to claim13, wherein an orthographic projection of the emergent light grating onthe substrate is positioned within an orthographic projection, on thesubstrate, of a sub-prism of the plurality of sub-prisms that has amaximum refractive index in the optical element.
 15. The reflection-typeliquid crystal display system according to claim 11, wherein theplurality of prisms are separated from one another with a separationdistance which is at least maintained so that a light propagation pathcorresponding to one of the plurality of prisms has no effect onrespective light propagation paths corresponding to other prisms of theplurality of prisms.
 16. The reflection-type liquid crystal displaysystem according to claim 11, wherein a sub-prism of the plurality ofsub-prisms of each prism having a maximum refractive index among theplurality of sub-prisms is larger than other sub-prisms of the pluralityof sub-prisms in thickness.
 17. The reflection-type liquid crystaldisplay system according to claim 16, wherein a thickness of thesub-prism having the maximum refractive index among the plurality ofsub-prisms is not less than a sum of respective thicknesses of the othersub-prisms.
 18. The reflection-type liquid crystal display systemaccording to claim 11, wherein a difference between the refractiveindexes of two adjacent ones of the plurality of sub-prisms is smallerthan 0.05.
 19. The reflection-type liquid crystal display systemaccording to claim 11, wherein a cross section of each of the prismstaken by a plane that extends along the first direction and isperpendicular to the surface of the substrate is a rectangle.
 20. Thereflection-type liquid crystal display system according to claim 11,wherein a cross section of each of the prisms taken by a plane thatextends along the first direction and is perpendicular to the surface ofthe substrate is an arc, and a respective convex surface of each of theplurality of prisms faces toward the first direction.